Consolidated Statements of Stockholders' Equity - USD ($)  $ in Millions  | 
Total  | 
Common Stock  | 
Treasury Stock  | 
Additional Paid-in Capital  | 
Accumulated Deficit  | 
Non-controlling Interest  | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2018 | 
 
 | 
257,000,000.0
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2018 | 
 
 | 
 
 | 
12,800,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2018 | 
$ 1,929
 | 
$ 1
 | 
$ (406)
 | 
$ 4,035
 | 
$ (4,156)
 | 
$ 2,455
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units, shares | 
 
 | 
600,000
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units | 
0
 | 
$ 0
 | 
$ 0
 | 
0
 | 
0
 | 
0
 | 
| Share-based compensation | 
28
 | 
$ 0
 | 
$ 0
 | 
28
 | 
0
 | 
0
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock | 
 
 | 
(200,000)
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares | 
 
 | 
 
 | 
200,000
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost | 
(12)
 | 
$ 0
 | 
$ (12)
 | 
0
 | 
0
 | 
0
 | 
| Net income attributable to non-controlling interest | 
196
 | 
0
 | 
0
 | 
0
 | 
0
 | 
196
 | 
| Distributions and dividends to non-controlling interest | 
(144)
 | 
0
 | 
0
 | 
0
 | 
0
 | 
(144)
 | 
| Net income | 
141
 | 
$ 0
 | 
$ 0
 | 
0
 | 
141
 | 
0
 | 
| Common Stock, Shares, Outstanding, End of Period at Mar. 31, 2019 | 
 
 | 
257,400,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Mar. 31, 2019 | 
 
 | 
 
 | 
13,000,000.0
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Mar. 31, 2019 | 
2,138
 | 
$ 1
 | 
$ (418)
 | 
4,063
 | 
(4,015)
 | 
2,507
 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2018 | 
 
 | 
257,000,000.0
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2018 | 
 
 | 
 
 | 
12,800,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2018 | 
$ 1,929
 | 
$ 1
 | 
$ (406)
 | 
4,035
 | 
(4,156)
 | 
2,455
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Shares repurchased, at cost, shares | 
44,600
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Net income attributable to non-controlling interest | 
$ 312
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Net income | 
27
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2019 | 
 
 | 
257,500,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2019 | 
 
 | 
 
 | 
13,000,000.0
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Jun. 30, 2019 | 
2,023
 | 
$ 1
 | 
$ (423)
 | 
4,097
 | 
(4,129)
 | 
2,477
 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Mar. 31, 2019 | 
 
 | 
257,400,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Mar. 31, 2019 | 
 
 | 
 
 | 
13,000,000.0
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Mar. 31, 2019 | 
2,138
 | 
$ 1
 | 
$ (418)
 | 
4,063
 | 
(4,015)
 | 
2,507
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units, shares | 
 
 | 
100,000
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units | 
0
 | 
$ 0
 | 
$ 0
 | 
0
 | 
0
 | 
0
 | 
| Share-based compensation | 
33
 | 
$ 0
 | 
$ 0
 | 
33
 | 
0
 | 
0
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock | 
 
 | 
0
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares | 
 
 | 
 
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost | 
$ (2)
 | 
$ 0
 | 
$ (2)
 | 
0
 | 
0
 | 
0
 | 
| Shares repurchased, at cost, shares | 
44,600
 | 
0
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Shares repurchased, at cost | 
$ (3)
 | 
$ 0
 | 
$ (3)
 | 
0
 | 
0
 | 
0
 | 
| Net income attributable to non-controlling interest | 
116
 | 
0
 | 
0
 | 
0
 | 
0
 | 
116
 | 
| Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt | 
1
 | 
0
 | 
0
 | 
1
 | 
0
 | 
0
 | 
| Distributions and dividends to non-controlling interest | 
(146)
 | 
0
 | 
0
 | 
0
 | 
0
 | 
(146)
 | 
| Net income | 
(114)
 | 
$ 0
 | 
$ 0
 | 
0
 | 
(114)
 | 
0
 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2019 | 
 
 | 
257,500,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2019 | 
 
 | 
 
 | 
13,000,000.0
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Jun. 30, 2019 | 
$ 2,023
 | 
$ 1
 | 
$ (423)
 | 
4,097
 | 
(4,129)
 | 
2,477
 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2019 | 
253,600,000
 | 
253,600,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2019 | 
17,100,000
 | 
 
 | 
17,100,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2019 | 
$ 2,435
 | 
$ 1
 | 
$ (674)
 | 
4,167
 | 
(3,508)
 | 
2,449
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units, shares | 
 
 | 
2,100,000
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units | 
0
 | 
$ 0
 | 
$ 0
 | 
0
 | 
0
 | 
0
 | 
| Share-based compensation | 
29
 | 
$ 0
 | 
$ 0
 | 
29
 | 
0
 | 
0
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock | 
 
 | 
(700,000)
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares | 
 
 | 
 
 | 
700,000
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost | 
(39)
 | 
$ 0
 | 
$ (39)
 | 
0
 | 
0
 | 
0
 | 
| Shares repurchased, at cost, shares | 
 
 | 
(2,900,000)
 | 
2,900,000
 | 
 
 | 
 
 | 
 
 | 
| Shares repurchased, at cost | 
(155)
 | 
$ 0
 | 
$ (155)
 | 
0
 | 
0
 | 
0
 | 
| Net income attributable to non-controlling interest | 
228
 | 
0
 | 
0
 | 
0
 | 
0
 | 
228
 | 
| Distributions and dividends to non-controlling interest | 
(154)
 | 
0
 | 
0
 | 
0
 | 
0
 | 
(154)
 | 
| Net income | 
375
 | 
$ 0
 | 
$ 0
 | 
0
 | 
375
 | 
0
 | 
| Common Stock, Shares, Outstanding, End of Period at Mar. 31, 2020 | 
 
 | 
252,100,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Mar. 31, 2020 | 
 
 | 
 
 | 
20,700,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Mar. 31, 2020 | 
$ 2,719
 | 
$ 1
 | 
$ (868)
 | 
4,196
 | 
(3,133)
 | 
2,523
 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2019 | 
253,600,000
 | 
253,600,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2019 | 
17,100,000
 | 
 
 | 
17,100,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2019 | 
$ 2,435
 | 
$ 1
 | 
$ (674)
 | 
4,167
 | 
(3,508)
 | 
2,449
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Shares repurchased, at cost, shares | 
2,875,376
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Net income attributable to non-controlling interest | 
$ 435
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Net income | 
$ 572
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2020 | 
252,200,000
 | 
252,200,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2020 | 
20,700,000
 | 
 
 | 
20,700,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Jun. 30, 2020 | 
$ 2,996
 | 
$ 1
 | 
$ (870)
 | 
4,227
 | 
(2,936)
 | 
2,574
 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Mar. 31, 2020 | 
 
 | 
252,100,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, Beginning of Period at Mar. 31, 2020 | 
 
 | 
 
 | 
20,700,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, Beginning of Period at Mar. 31, 2020 | 
2,719
 | 
$ 1
 | 
$ (868)
 | 
4,196
 | 
(3,133)
 | 
2,523
 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units, shares | 
 
 | 
100,000
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Vesting of restricted stock units and performance stock units | 
0
 | 
$ 0
 | 
$ 0
 | 
0
 | 
0
 | 
0
 | 
| Share-based compensation | 
31
 | 
$ 0
 | 
$ 0
 | 
31
 | 
0
 | 
0
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock | 
 
 | 
0
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares | 
 
 | 
 
 | 
0
 | 
 
 | 
 
 | 
 
 | 
| Issued shares withheld from employees related to share-based compensation, at cost | 
$ (2)
 | 
$ 0
 | 
$ (2)
 | 
0
 | 
0
 | 
0
 | 
| Shares repurchased, at cost, shares | 
0
 | 
 
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Net income attributable to non-controlling interest | 
$ 207
 | 
0
 | 
0
 | 
0
 | 
0
 | 
207
 | 
| Distributions and dividends to non-controlling interest | 
(156)
 | 
0
 | 
0
 | 
0
 | 
0
 | 
(156)
 | 
| Net income | 
$ 197
 | 
$ 0
 | 
$ 0
 | 
0
 | 
197
 | 
0
 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2020 | 
252,200,000
 | 
252,200,000
 | 
 
 | 
 
 | 
 
 | 
 
 | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2020 | 
20,700,000
 | 
 
 | 
20,700,000
 | 
 
 | 
 
 | 
 
 | 
| Stockholders' Equity, End of Period at Jun. 30, 2020 | 
$ 2,996
 | 
$ 1
 | 
$ (870)
 | 
$ 4,227
 | 
$ (2,936)
 | 
$ 2,574
 |